Fc-FAD

Scheme 8. The Biickmann N6-(2-aminoethyl)-FAD (H2NCH2CH2-FAD) (109) and its ferrocene derivative Fc-FAD loaded into apo-GO (108).

FIGURE 6-9 Electrical contact of a flavoenzyme by its reconstitution with a relay-FAD semisynthetic cofactor. Fc = ferrocene. (Reproduced with permission from reference 2.)... 

Additional information about this Fc GO preparation has been reported elsewhere (112). The intramolecular electron transfer rate constant kmirn calculated using Eq. (36) equals 40 s-1 and is by a factor of 50 higher than that for the randomly modified GO (104). The distance separating the ferrocene unit and FAD in Fc GO is believed to be ca. 19 A, by 2 A shorter than in the most effective electrically contacted enzyme generated by the random modification of GO by ferrocene units. This information supports the hypothesis about the key locations of ferrocene groups that play the dominant role in the electrocatalysis (104). 

Figure 28. (A) The photoswitchable oxidation of glucose by immobilized GOx reconstituted with a spiropyran-modified FAD and with ferrocenccarboxylic acid as a dilfusional electron mediator. (B) Cyclic voltammograms of the modified electrode in the presence of glucose (50 mM), FC-CO2H (50 pM) and with the electrode (a, c) in the spiro (SP) state, and (b, d) in the merocyanine (MRH+) state. Recorded in 0.01 M phosphate buffer, pH 7.3 potential scan rate, 5 mV s . Inset switching behavior of the electrocatalytic current as a function of the state of the photoisomerizable group.

NADPH dehydrogenase is an enzyme system, which apparently consists of multiple components localised in the plasmalemma, in specific granules, and in the cytosol of phagocytes. A number of components has been suggested to be involved in the redox chain of NADPH dehydrogenase, including flavine adenine dinucleotide (FAD), quinones, and a phagocyte-specific cytochrome referred as cytochrome fc.245. 

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